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The unique hydrologic conditions characterizing riparian ecosystems in dryland (arid and semi-arid) areas help maintain high biodiversity and support high levels of primary productivity compared to associated uplands. In western North America, many riparian ecosystems have been damaged by altered flow regimes (e.g., impoundments and diversions) and over utilization of water resources (e.g., groundwater pumping for agriculture and human consumption). This has led some state and national governments to provide occasional environmental flows to address the declining condition of such riparian systems. In a historic agreement between the United States and Mexico, 130 million cubic meters (mcm) of water was released...
Managing streamflow is a widely-advocated approach to provide conditions necessary for seed germination and seedling establishment of trees in the willow family (Salicaceae). Experimental flow releases to the Colorado River delta in 2014 had a primary objective of promoting seedling establishment of Fremont cottonwood (Populus fremontii) and Goodding's willow (Salix gooddingii). We assessed seed germination and seedling establishment of these taxa as well as the non-native tamarisk (Tamarix spp.) and native seepwillow shrubs (Baccharis spp.) in the context of seedling requirements and active land management (land grading, vegetation removal) at 23 study sites along 87 river km. In the absence of associated active...
In the southwestern U.S., many riparian ecosystems have been altered by dams, water diversions, and other anthropogenic activities. This is particularly true of the Colorado River, where numerous dams and agricultural diversions have affected this water course, especially south of the U.S.–Mexico border. In the spring of 2014, 130 million cubic meters of water was released to the lower Colorado River Delta in Mexico. To understand the impact of this pulse flow release on vegetation in the delta's riparian corridor, we analyzed a modified form of Landsat 8 Operational Land Imager (OLI) Normalized Difference Vegetation Index (NDVI*) data. We assessed greenup during the growing period and estimated actual evapotranspiration...
In 2014, the United States and Mexico jointly delivered an environmental flow to the Colorado River Delta, as authorized in a 2012 binational water management agreement known as Minute 319. The agreement specified a volume of water, the source of the water, that the water should be delivered as a pulse flow, and that the objectives of the pulse flow were to pilot environmental restoration and learn about the hydrologic and ecological responses to water delivery into the Colorado River Delta. The Minute did not specify the characteristics of the pulse flow, but rather specified a process, calling on a group of stakeholders, including federal, state, and local water managers as well as non-governmental conservation...
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These data were compiled for a manuscript that examines the riverine food-web structure of the Colorado River below Glen Canyon dam to its confluence with Lake Mead. Tissue from primary producers (vascular plants and algae) and consumers (aquatic invertebrates and fish) were collected before and after monsoon floods in 2006 along the 388 kilometer segment of the Colorado River in the Southwest US. Tissue samples were dried, ground, and analyzed for δ13C, δ15N, and δ2H stable isotope signatures and percent carbon and nitrogen. Analysis of these data focused on determining the proportion of terrestrial (allochthonous) vs. aquatic (autochthonous) organic matter sources at the base of the food web, trophic diversity...


    map background search result map search result map Food Web Data, Colorado River Corridor, Grand Canyon, Arizona, 2006 Food Web Data, Colorado River Corridor, Grand Canyon, Arizona, 2006